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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
311

Miljöbilsanvändning : En attityd- och beteendeundersökning hos ägare av bilar drivna med förnybara drivmedel

Larsson, Martin January 2008 (has links)
The aim of this report is to give a picture of how attitudes and behaviours of owners of environment cars look like and how they can be influenced. The alignment lies on environmental cars which run on biogas and ethanol which both are renewable fuels. The starting point is to sort out if it is environmental thinking that controls the choice and use of an environmental car. The feeling is that there are many other factors that can be more controlling, for example the price and the quality of the car. The result of the questionnaire survey which is the foundation of the report shows however that those who buy an environmental car do it mostly because of environmental reasons. Also the daily choice of fuel is mainly environmentally influenced; it however shows that there is dissatisfaction with the high fuel consumption, the short reach and above all the high price of ethanol. It also shows that the source of information which had the biggest impact on the choice to buy an environmental car is the mass media and that the most influencing policy instruments is the price, partly the cheaper on renewable fuel and the more costly fossil fuel. In general the environmental car owners are also positively inclined to using policy instruments of various kinds in order to increase the proportion of environmental cars on our roads. The conclusion becomes thus that the original feeling is incorrect and that environment cars have not at all lost credibility, not anyway on the level that has been investigated in this report. / Syftet med den här rapporten är att gen en bild av hur attityder och beteenden hos ägare av miljöbilar ser ut samt hur de kan påverkas. Inriktningen ligger på miljöbilar drivna med biogas och etanol vilka båda är förnyelsebara bränslen. Utgångspunkten är att reda ut om det är miljötänkandet som styr val och användning av en miljöbil. Känslan är att det finns många andra faktorer som kan vara mer styrande, exempelvis pris och kvalitet på bilen. Resultatet av den enkätundersökning som ligger till grund för rapporten visar dock att de som köper en miljöbil gör det till största delen på grund av miljömässiga orsaker. Även det dagliga valet av bränsle påverkas mestadels av miljömässiga orsaker, det visar sig dock att det finns ett missnöje med den höga bränsleförbrukningen, den korta räckvidden och framförallt det höga priset på etanol. Det visar sig också att den källa till information som haft den största påverkan vid valet att köpa en miljöbil är media samt att det mest påverkande styrmedlet är priset, dels det billigare på förnyelsebara bränslen samt det dyrare på fossila bränslen. Generellt är miljöbilägarna också positivt inställda till att använda styrmedel av olika slag för att öka andelen miljöbilar på vägarna. Slutsatsen blir således att den ursprungliga känslan är felaktig och att miljöbilar inte alls tappat i trovärdighet, i alle fall inte på det plan som granskas i denna rapport.
312

Development of simulation tools, control strategies, and a hybrid vehicle prototype

Pei, Dekun 14 November 2012 (has links)
This thesis (1) reports the development of simulation tools and control strategies for optimizing hybrid electric vehicle (HEV) energy management, and (2) reports the design and testing of a hydraulic hybrid school bus (HHB) prototype. A hybrid vehicle is one that combines two or more energy sources for use in vehicle propulsion. Hybrid electric vehicles have become popular in the consumer market due to their greatly improved fuel economy over conventional vehicles. The control strategy of an HEV has a paramount effect on its fuel economy performance. In this thesis, backward-looking and forward-looking simulations of three HEV architectures (parallel, power-split and 2-mode power-split) are developed. The Equivalent Cost Minimization Strategy (ECMS), which weights electrical power as an equivalent fuel usage, is then studied in great detail and improvements are suggested. Specifically, the robustness of an ECMS controller is improved by linking the equivalence factor to dynamic programming and then further tailoring its functional form. High-fidelity vehicle simulations over multiple drive-cycles are performed to measure the improved performance of the new ECMS controller, and to show its potential for online application. While HEVs are prominent in the consumer market and studied extensively in current literature, hydraulic hybrid vehicles (HHVs) only exist as heavy utility vehicle prototypes. The second half of this thesis reports design, construction, and testing of a hydraulic hybrid school bus prototype. Design considerations, simulation results, and preliminary testing results are reported, which indicate the strong potential for hydraulic hybrids to improve fuel economy in the school bus vehicle segment.
313

Topology Optimization of Vehicle Body Structure for Improved Ride & Handling

Lövgren, Sebastian, Norberg, Emil January 2011 (has links)
Ride and handling are important areas for safety and improved vehicle control during driving. To meet the demands on ride and handling a number of measures can be taken. This master thesis work has focused on the early design phase. At the early phases of design, the level of details is low and the design freedom is big. By introducing a tool to support the early vehicle body design, the potential of finding more efficient structures increases. In this study, topology optimization of a vehicle front structure has been performed using OptiStruct by Altair Engineering. The objective has been to find the optimal topology of beams and rods to achieve high stiffness of the front structure for improved ride and handling. Based on topology optimization a proposal for a beam layout in the front structure area has been identified. A vital part of the project has been to describe how to use topology optimization as a tool in the design process. During the project different approaches has been studied to come from a large design space to a low weight architecture based on a beam-like structure. The different approaches will be described and our experience and recommendations will be presented. Also the general result of a topology-optimized architecture for vehicle body stiffness will be presented.
314

Electric cars : The climate impact of electric cars, focusing on carbon dioxide equivalent emissions

Ly, Sandra, Sundin, Helena, Thell, Linda January 2012 (has links)
This bachelor thesis examines and models the emissions of carbon dioxide equivalents of the composition of automobiles in Sweden 2012. The report will be based on three scenarios of electricity valuation principles, which are a snapshot perspective, a retrospective perspective and a future perspective. The snapshot perspective includes high and low values for electricity on the margin, the retrospective perspective includes Nordic and European electricity mix and the future perspective includes electricity on the margin for modest and high climate goals at 2030. The study is applied to an upcoming climate smart district, Brunnshög in Lund, and the goal is to determine the amount of emissions of carbon dioxide equivalents for the mentioned alternatives. The environmental effects depends largely on the fuel consumption for the compared types of cars and what electricity valuation principle that is used. The car fleet of 2012 generated 10 300 tonnes of carbon dioxide emissions. The future car fleet generated 400 tonnes of emissions for Nordic electricity mix, 3 200 tonnes for European electricity mix, 3 100 tonnes for electricity on the margin with low values, 5 800 tonnes for electricity on the margin with high values, 1 200 tonnes for electricity on the margin at 2030 for high climate goals and 4 600 tonnes for electricity on the margin at 2030 for modest climate goals. The emissions of carbon dioxide equivalents are at least halved in Brunnshög if 100 % electric cars are used instead of the composition of petrol, diesel and ethanol cars that are primarily used in Sweden 2012. Hence, the result shows that the electric car is very beneficial from an environmental and health perspective, compared to the composition of cars in Sweden 2012. However, how beneficial the electric car is, largely depends on the fuel consumption for both the electric car and the alternative compared with. Although to be able to increase the use of electric cars there are many challenges that need to be dealt with. In order to increase the use of electric cars, it will require further work in the development of batteries, expansion of charging points and other incentives, such as legislation and investments. It will also require a significant technology development to increase the range of the electric car. A natural step in the transition phase could be plug-in hybrids. It is also important to continue to implement climate smart districts, such as Brunnshög in Lund.
315

Kriminalitetens geografi : vardagsbrottslighetens spatiala fördelning i Borlänge

Axelsson, Henrik January 2008 (has links)
The aim of this thesis is to describe and analyze the geographical distribution of everyday criminality in the town of Borlänge during the year 2002 and to analyze which measures to be taken in the physical social planning to decrease this everyday criminality there. The term everyday criminality is here to be understood as those categories of crime that appear most frequently in the records of reports to the police every year. Here two kinds of crime have been in focus, thefts from cars and office burglary.In fulfilling this aim two main questions have been answered. The first one is how the everyday criminality was distributed geographically in the town of Borlänge during the year 2002. The second one is which measures to be taken in the physical social planning to decrease this everyday criminality in the town of Borlänge.In order to answer the first question a spatial autocorrelation analysis, Local Moran LISA has been used. This method is based on the measurement Moran´s I and shows the spatial autocorrelation for every single location. To answer the second question three different theories of crime prevention through environmental design have been studied and applied in the analysis. These are Jane Jacobs’ ideas about ”the living city”, Oscar Newman´s ideas about ”defensible space” and Ronald V. Clarke´s theories about crime prevention.The major conclusions that can be drawn from this thesis are that the risk of being exposed to thefts from cars, during the analyzed time period, was highest in Centrum and Hagalund and their surroundings. The lowest risk of being exposed to this type of crime was found in Domnarvet and Islingby, during the year 2002. The highest risk of being a victim of the crime office burglary was found in Hagalund and its surroundings and in the single area of Kvarnsveden. The corresponding lowest risk was found in Lergärdet and its surroundings and in Norra Backa and Kupolen. The measures that should be taken in order to decrease these types of criminality can be divided into overall changes and place-specific changes. When it comes to the crime thefts from cars a more attractive central business district, a better view of parking lots from nearby buildings, dividing of larger parking lot zones into smaller ones, migration of hidden parking lots and stronger access control to parking lots where problems with this kind of crime have occurred have been suggested as overall changes. The corresponding place-specific changes are to remove vegetation that is blocking the view, better lighting and to put up signs with information about increased risk of exposure to crime at parking lots with the most problems. To decrease the amount of office burglaries overall changes as to create a better view of the area from nearby surroundings, move bigger office compartments or divide them into smaller units, rebuild characteristic buildings and increase security by strengthening the access control to offices with these kinds of problems could be useful. Finally there are possibilities to decrease office burglary by using place-specific measures as surveillance cameras combined with signs containing information about these, high fences and better lighting around the buildings where a higher risk of being exposed to this kind of criminality is present.
316

Thermodynamics of metal hydrides for hydrogen storage applications using first principles calculations

Kim, Ki Chul 02 July 2010 (has links)
Metal hydrides are promising candidates for H2 storage, but high stability and poor kinetics are the important challenges which have to be solved for vehicular applications. Most of recent experimental reports for improving thermodynamics of metal hydrides have been focused on lowering reaction enthalpies of a metal hydride by mixing other compounds. However, finding out metal hydride mixtures satisfying favorable thermodynamics among a large number of possible metal hydride mixtures is inefficient and thus a systematic approach is required for an efficient and rigorous solution. Our approaches introduced in this thesis allow a systematic screening of promising metal hydrides or their mixtures from all possible metal hydrides and their mixtures. Our approaches basically suggest two directions for improving metal hydride thermodynamics. First, our calculations for examining the relation between the particle size of simple metal hydrides and thermodynamics of their decomposition reactions provide that the relation would depend on the total surface energy difference between a metal and its hydride form. It ultimately suggests that we will be able to screen metal hydride nanoparticles having favorable thermodynamics from all possible metal hydrides by examining the total surface differences. Second, more importantly, we suggest that our thermodynamic calculations combined with the grand canonical linear programming method and updated database efficiently and rigorously screen potential promising bulk metal hydrides and their mixtures from a large collection of possible combinations. The screened promising metal hydrides and their mixtures can release H2 via single step or multi step. Our additional free energy calculations for a few selected promising single step reactions and their metastable paths show that we can identify the most stable free energy paths for any selected reactant mixtures. In this thesis, we also demonstrate that a total free energy minimization method can predict the possible evolution of impurity other than H2 for several specified mixtures. However, it is not ready to predict reaction thermodynamics from a large number of compounds.
317

Enhancement of Raman signals : coherent Raman scattering and surface enhanced Raman spectroscopy

Chou, He-Chun 06 July 2012 (has links)
Raman spectroscopy is a promising technique because it contains abundant vibrational chemical information. However, Raman spectroscopy is restricted by its small scattering cross section, and many techniques have been developed to amplify Raman scattering intensity. In this dissertation, I study two of these techniques, coherent Raman scattering and surface enhanced Raman scattering and discuss their properties. In the first part of my dissertation, I investigate two coherent Raman processes, coherent anti-Stokes Raman scattering (CARS) and stimulated Raman scattering (SRS). In CARS project, I mainly focus on the molecular resonance effect on detection sensitivity, and I find the detection sensitivity can be pushed into 10 [micromolar] with the assistance of molecular resonance. Also, I am able to retrieve background-free Raman spectra from nonresonant signals. For SRS, we develop a new SRS system by applying spectral focusing mechanism technique. We examine the feasibility and sensitivity of our SRS system. The SRS spectra of standards obtained from our system is consistent with literature, and the sensitivity of our system can achieve 10 times above shot-noise limit. In second part of this dissertation, I study surface enhanced Raman scattering (SERS) and related plasmonic effects. I synthesize different shapes of nanoparticles, including nanorod, nanodimer structure with gap and pyramids by template method, and study how electric field enhancement effects correlate to SERS by two photon luminescence (TPL). Also, I build an optical system to study optical image, spectra and particle morphology together. I find that SERS intensity distribution is inhomogeneous and closely related to nanoparticle shape and polarization direction. However, TPL and SERS are not completely correlated, and I believe different relaxation pathways of TPL and SERS and coupling of LSPR and local fields at different frequencies cause unclear correlation between them. / text
318

Analysis of the fuel economy potential of a direct injection spark ignition engine and a CVT in an HEV and a conventional vehicle based on in-situ measurements

Min, Byung-Soon 28 August 2008 (has links)
Not available / text
319

Best practice for personnel, material and rock transportation in ultra deep level gold mines.

Rupprecht, Steven Michael. January 2003 (has links)
Ultra deep mining presents many challenges to the mining engineer, one of which is the logistics to support mining operations quickly and efficiently. Typically, Witwatersrand gold mines operate at depths in excess of 2000 m with stoping taking place to 3500 m and investigations underway to mine to a depth of 5000 m. As mining progresses deeper and further from the shaft, the role of logistics becomes increasingly important if production targets are to be achieved. Access to the workings is often via sub vertical and even tertiary subvertical shaft systems with working faces as far as five kilometers from the shaft. It is inevitable therefore, that distance will negatively impact the working time available at the stope face, material transportation and distribution, as well as the removal of broken ore. Possible solutions to these logistical problems may be found in the use of different transportation systems or by applying sound design and operational principles to transportation systems, both in the horizontal and instope areas. This thesis investigates the challenges of logistics for ultra deep level gold mining in the Witwaterstrand basin for mining layouts planning to mine between 3000 m and 5000 m underground with typical horizontal distances of over 3000 m. The transportation needs analysis recognised that vertical transportation is a wellmanaged and organised system and is mainly the same for both shallow and deep level operations. As a result of this, the thesis only focuses on the logistical issues of the horizontal and in-stope processes. The literature review indicates that the majority of work previously conducted on transportation focused around the area of horizontal transportation with limited inputs to in-stope transportation systems. The review concludes that the traditional locomotive transportation system is the most applicable mode of horizontal transportation. Thus, special emphasis is given to trackbound transportation. An integrated approach is taken towards mine transportation advocating that underground logistics be considered as equally important as any other discipline, Le. rock engineering, ventilation, etc. In addition, the transportation process should consider each area equally important. All to often, the transportation of rock is considered of paramount importance over the transportation of personnel and material. Thus, the planning any transportation system should incorporate personnel, material and rock. To enable this, scheduling, communication and control are important with special attention required for transfer points in the transportation system. As each site has its own particular requirement, thus the final transportation systems must be drawn up based on the specific requirements of each mine. A guideline is proposed for the design of ultra deep level underground transport systems for personnel, material and rock transportation. Thus, providing mining engineers with sufficient information and data to select an appropriate transportation system to meet specific mine requirements. The thesis highlights areas requiring consideration by mine engineers when designing a transportation system from shaft to the working face. / Thesis (Ph.D.)-University of Natal, Durban, 2003.
320

Investigation Of Emission Factors Of Non-methane Hydrocarbons For Some Widely Used Passenger Cars In Turkey

Onoglu, Irem 01 September 2004 (has links) (PDF)
The objectives of this study are to measure the non-methane volatile organic carbon (NMVOC&#039 / s) emissions from passenger cars in Turkey having gasoline engines, to determine emission factors of these vehicles for BTEX compounds and comparison of emission factors obtained in this study with the emission factors of the other countries. This study was conducted in two parts: The first part was to determine the categories of passenger cars widely used in Turkey, and also to determine the average carbon monoxide (CO) and hydrocarbon (HC) emissions at idle condition for these car types based on the exhaust emission measurements of Ankara &Ccedil / evre Koruma Vakfi (AN&Ccedil / EVA). The second part of the study was to analyze the gas composition of exhaust gasses at different road conditions for BTEX components by using gas chromatography. The results of the study have shown that the cars named under &lsquo / &lsquo / Tofas&rsquo / &rsquo / constitute 31.5% and &lsquo / &lsquo / Fiat&rsquo / &rsquo / 13.1% of the total cars in Turkey and they are manufactured by the same company. Therefore, studies have been performed with &lsquo / &lsquo / Tofas/Fiat&rsquo / &rsquo / cars. The highest emission factors among hydrocarbons investigated in this study were found for toluene and m-xylene. Generally, as driving speed increases the emissions of HC&rsquo / s are found to decrease in concentration. It was interesting to note that the highest emissions occur at 30 km/hr speed which is the mostly used speed in crowded streets and busy intersections. Therefore, it was concluded that it is very important to take measures for emissions in the city traffic. Cold start emissions were also found to be higher than the hot start emissions.

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